Apparatus for investing under vacuum dental wax patterns or any other type of pattern



C. E. POMES APPARATUS FOR INVESTING UNDER VACUUM DENTAL WAX May 16, 1950 PATTERNS OR ANY OTHER TYPE OF PATTERN Filed Sept. 2, 1947- J r z a j j 4 A \\&\ or\\\ A A N \A a 4 4 0 l Q \o m .YHN A L .1?! Z a z w HWIIHIH Patented May 16, 1950' UNITED STATES PATENT OFFICE APPARATUS FOR INVESTING UNDER VAC- UUM DENTAL WAX PATTERNS OR ANY OTHER TYPE OF PATTERN Carlos E. Poms, Chicago, Ill.

Application September 2, 1947, Serial No. 771,636

1 Claim. 1

This invention relates to an instrument for investing under vacuum dental wax patterns or any other type of pattern.

An object of this invention is to provide an instrument. to invest dental wax patterns or any other type of pattern under vacuum to produce dental castings or any other type of casting. Said instrument can likewise be used to eliminate the wax from the investment mold.

Specifically in the construction of dental in.- lays, either by the dentist or dental laboratory, it is desirable to remove the air from the investment material which surrounds the mold, otherwise air bubbles are likely to be formed which will appear in the inlay. This is decidedly objectionable in that an inlay with nodules will not fit the tooth cavity.

Various methods have been used to provide for the removing of air from the investment mix but these. are objectionable in that they perform inefficiently. Furthermore, some. require large and expensive mechanism and special installation.

Another object of this invention therefore, is to provide a simple, inexpensive and compact apparatus which. can rapidly, efliciently and economically evacuate the air from the investment material and eliminate the air bubbles so as to form a perfect mold, which apparatus can also be used to eliminate the wax from the investment material after the mold is formed. Said apparatus can also be used to invest wax patterns with any dental investment complying with present standards.

Other objects will become apparent as this description progresses.

In the drawings:

Fig. l is a cross sectional view of my apparatus.

Fig. 2 is a view partly in cross section with the parts in position for removal of the wax pattern, and

Fig. 3 is a fragmentary view showing another form of apparatus in which the exhaust tube can be used.

The procedure in forming a dental inlay will now be described. The wax is inserted in the tooth cavity or a replica thereof and is therein shaped to fill such cavity, after which it is removed and a gold alloy inlay or casting is formed of such wax pattern, as follows. The wax pattern 9 is mounted on a metal sprue pin III which is inserted and supported on a sprue'base I2. The sprue base I2 is formed preferably of rubber and is shaped to provide a central opening M, an annular recess l 6 and an annular shoulder H. The

bottom or underside of the base has an enlarged cavity I8 and an annular shoulder portion 20. A ring or flask 22 having an asbestos liner 24 which extends beyond the top of the flask is next inserted in the recess I6 of the sprue base and forms a seal tight fit therewith. The dental investment material, indicated by the numeral 2!, is separately mixed, with water and the flask-is filled with the investment material over and above the top of the flask as shown.

A resilient cylindrical member 26 preferably closed at the upper end and having an open bot!- tom and an inwardly extending flange portion 28 is positioned on the flask 22 after first overlapping the asbestos, as shown at 25 to form a tight fit between the flask and cylindrical member. The fiange extends inwardly of the asbestos lining to cover same. The cylindrical. member has one or more openings 30 adjacent the top. An exhaust tube 32 made of any suitable material is positioned over the cylinder and rests against the annular shoulder H on the sprue base to form a seal tight fit. The opening 30 communicates with the interior of the exhaust tube. The exhaust tube has an extension 34 to which is connected a flexible pipe 36 whose opposite end is attached to any vacuum producing apparatus producing at least a vacuum of 28 inches of mercury This has the advantage in that it may be secured to an inexpensive filter pump which in turn is secured to a water faucet for creating a vacuum in the apparatus. The pipe 36 can also be connected to any other type of pump, such as a motor pump.

In the extension 34 I provide a filter 38 to prevent any of the investment from being drawn up past the filter and there is also a valve 40 in the pipe for closing the communication between the exhaust tube and the pump. When the vacuum is created and the air exhausted from the exhaust tube 32, cylindrical member 26 and the investment material 2|, the investment material will tend to rise upwardly outside the flask. The apparatus is then vibrated for about thirty seconds allowing the investment material to settle and perfectly fill the flask 22. The valve 40 is then closed and the unit is slightly vibrated for about ten seconds, thus insuring a smooth surface on the top of the investment. The exhaust tube 32 and cylindrical member 26 are then removed and the portion 25 of the asbestos liner trimmed off in such a way that the investment seals the upper end of the flask. The investment material is allowed to set or harden for approximately thirty minutes, depending upon the type of investment material used. The sprue pin ll) is withdrawn from the bottom of the base leavin the wax pattern 9 in the hardened investment and providing a passageway or gate 4|.

When it is desirable to eliminate the wax by means of boiling water as is understood in the art, the sprue base with the flask and investment material in place is inverted, as shown in Fig. 2, and the exhaust tube 32 is inserted on the shoulder 20 of the sprue base making a seal tight fit therewith.

The flask 22 is immersed in boiling water and a vacuum is then again created in the exhaust tube 32 by turning on the vacuum pump and opening the valve 40 as heretofore, and the wax 9 in the investment will be drawn into the exhaust tube 32 through the gate opening 4| in the investment and will be prevented from passing into the flexible pipe 36 by the filter 38. The parts are then disassembled and the procedure in constructin the metal casting or inlay is followed as is well understood in the art.

I have found that the resilient cylindrical member 26 can serve as an exhaust tube and that the exhaust tube 32 can be eliminated in the construction shown in Fig. 1. This can be accomplished by connecting a flexible pipe similar to the pipe 36 directly to the opening 30 of the cylindrical tube in a seal tight fit and providing a filter like 38 and a valve 40 in the flexible tube.

In Fig. 3 is shown another form in which the exhaust tube can be used. The sprue base I 2a and flask 22a are almost identical to those previously described and are assembled in exactly the same manner. However, the base I2a has a shoulder 20a on the bottom thereof of smaller circumference than the corresponding shoulder 20 on the sprue base [2 so as to accommodate the exhaust tube 32a. which is of the same diameter as the flask 22a. The flask is over-filled with the investing material 2la. The exhaust tube is connected to the top of the flask 220. by means of a rubber tubing 44 having a lateral flange 42 which rests on the overlapping portion 43 of the asbestos liner. This flange is interposed between the exhaust tube and the flask and extends inwardly of the asbestos liner in the flask. The top of the exhaust tube is likewise provided with a filter and a valve and is connected by a flexible pipe to a filter pump or vacuum producing apparatus.

The procedure for forming a mold in the investment material is similar to that previously described, likewise the removing of the wax pattern 9a can be accomplished by inverting the sprue base and connecting the exhaust tube to the base by means of the shoulder with which it forms a seal tight fit. The procedure is identical to that heretofore described in connection with the use of the apparatus shown in Figs. 1 and 2. a

I claim:

An apparatus for investing a dental wax pattern under vacuum and. eliminating the wax from the investment mold under vacuum, comprising a base having an annular recess and an annular shoulder exteriorly thereof, a pin protruding through and above said base for supporting a wax pattern, a flask supported in said recess on said base for receiving an investment material, an exhaust tube secured to said shoulder on said base and surrounding said flask, a vacuum producing member connected to said exhaust tube, a shoulder on the bottom side of said base to permit said base to be inverted and to secure said exhaust tube thereto with the base in inverted position when wax is removed by vacuum from the invested flask.

' CARLOS E. POMES.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

